F. J. Belda

Sevoflurane, but not propofol, reduces the lung inflammatory response and improves oxygenation in an acute respiratory distress syndrome model: a randomised laboratory study.

CONTEXT Acute respiratory distress syndrome is characterised by activation of the inflammatory cascade. The only treatment that reduces the mortality rate associated with this syndrome is lung protective ventilation, which requires sedation of patients. Sedation in critical care units is usually induced intravenously, although there is reason to believe that inhaled anaesthetics are a suitable alternative. Sevoflurane has recently been shown to modulate the lung inflammatory response in a model of lung injury more favourably than propofol. OBJECTIVE The goal of this study was to confirm whether or not sevoflurane is more effective than propofol in ameliorating the inflammatory response in an animal model of acute respiratory distress syndrome. DESIGN A prospective, randomised, controlled study. SETTING Research foundation laboratory at the Hospital Clínico Universitario, Valencia, Spain. EXPERIMENTAL ANIMALS Sixteen Landrace/large white crossbred pigs weighing 30 to 45 kg. INTERVENTIONS Animals were allocated randomly to one of two groups: one sedated with intravenous propofol 5 to 7 mg kg−1 h−1 (group P) and the other with sevoflurane, administered using an AnaConDa device to obtain an end-tidal concentration of 1.5% (group S). Monitoring, lung protective ventilation and anaesthetic management were identical in both groups. MAIN OUTCOME MEASURES The PaO2/FiO2 ratio and cytokine concentrations in bronchoalveolar lavage specimens were determined at 10, 150 and 240 min after confirmation of acute respiratory distress syndrome (PaO2/FiO2 <26.7 kPa). RESULTS At 240 min, median and interquartile range (IQR) concentrations of cytokines in bronchial lavage specimens in group S were lower than those in group P [interleukin-1&bgr; (IL-1&bgr;) 53, IQR 16–140 vs. 311, IQR 183–637 pg ml−1, P = 0.04; tumour necrosis factor-&agr; 347, IQR 161–433 vs. 552, IQR 475–649 pg ml−1, P = 0.04; and IL-6 101, IQR 76–282 vs. 580, IQR 369–701 pg ml−1, P = 0.03]. The polymorphonuclear neutrophil count was also lower in group S (P = 0.007), which also had a higher PaO2/FiO2 ratio. TRIAL REGISTRATION GE-015/09. CONCLUSION In an animal model of acute respiratory distress syndrome, sevoflurane ameliorates the lung inflammatory response and improves oxygenation to a greater extent than propofol.

Epidural anesthesia for laminectomy lead placement in spinal cord stimulation.

BACKGROUND:Spinal cord stimulation (SCS) is used to treat chronic pain and requires an awake patient for optimized lead positioning to locate paresthesias. Epidural anesthesia may be a suitable anesthetic but has not been evaluated. METHODS:We performed an open-label, prospective, observational, single-center study to evaluate the safety and efficacy of laminectomy lead placement under epidural anesthesia for the treatment of neuropathic chronic pain. RESULTS:The results in our study demonstrate that epidural anesthesia is a suitable technique for SCS lead implant. CONCLUSIONS:This is the first study using epidural anesthesia for SCS lead implants by laminectomy. The technique seems to be safe and effective.

effects of prone position on alveolar dead space and gas exchange during general anaesthesia in surgery of long duration

Background and objective: We investigated the effects of prone position on respiratory dead space and gas exchange in 14 anaesthetized healthy patients undergoing elective posterior spinal surgery of more than 3 h of duration. Methods: The patients received a total intravenous anaesthetic with propofol/remifentanil/cisatracurium. They were ventilated at a tidal volume of 8–10 mL kg−1, zero positive end‐expiratory pressure and an inspired oxygen fraction of 0.4. Physiological, airway and alveolar dead spaces were calculated by analysis of the volumetric capnography waveform. Measurements were made in supine position (20 min after the beginning of mechanical ventilation) and 30, 120 and 180 min after turning to prone position. Results: We found that the alveolar dead space/tidal volume ratio did not change. PaO2/FiO2 increased, although not statistically significantly. Dynamic compliance was reduced due to a reduction in tidal volume and an increase in plateau pressure. Conclusions: Patients undergoing surgery in prone position for a duration of 3 h under general anaesthesia including muscle relaxation and mechanical ventilation without positive end‐expiratory pressure have stable haemodynamics and no significant changes in the alveolar dead space to tidal volume ratio. Oxygenation tended to improve.

Protection strategies during cardiopulmonary bypass: ventilation, anesthetics and oxygen.

Purpose of review To provide an update of research findings regarding the protection strategies utilized for patients undergoing cardiopulmonary bypass (CPB), including perioperative ventilatory strategies, different anesthetic regimens, and inspiratory oxygen fraction. The article will review and comment on some of the most important findings in this field to provide a global view of strategies that may improve patient outcomes by reducing inflammation. Recent findings Postoperative complications are directly related to ischemia and inflammation. The application of lung-protective ventilation with lower tidal volumes and higher positive end-expiratory pressure reduces inflammation, thereby reducing postoperative pulmonary complications. Although inhalation anesthesia has clear cardioprotective effects compared with intravenous anesthesia, several factors can interfere to reduce cardioprotection. Hyperoxia up to 0.8 FiO2 may confer benefits without increasing oxidative stress or postoperative pulmonary complications. During the early postoperative period, inhalation anesthesia prior to extubation and the application of preventive noninvasive ventilation may reduce cardiac and pulmonary complications, improving patients’ outcomes. Summary Lung-protective mechanical ventilation, inhalation anesthesia, and high FiO2 have the potential to reduce postoperative complications in patients undergoing CPB; however, larger, well powered, randomized control trials are still needed.

Similar ventilation/perfusion between square and decelerating flow with end-inspiratory pause in an experimental setting with healthy neonatal lungs: 5AP3-9

Background and Goal of Study: The most adequate ventilatory mode in pediatric anesthesia has been controversial. Traditionally, pressure controlled ventilation (PCV) has been the most used ventilatory mode. It was thought that ventilation with PCV improved gas distribution producing better oxygenation. The goal of our study was to demonstrate that there are no dif ferences in ventilation/perfusion between square and decelerating flow with end-inspiratory pause when a recruitment maneuver is made and a level of positive end-expiratory pressure is set, in an experimental set ting with healthy neonatal lungs. Materials and Methods: An experimental, prospective, randomised, controlled study was conducted. 8 pigs weighing 3±0.1 kg were employed. Anaesthesia management and monitoring were identical in all animals. A PiCCO monitor was employed for haemodynamic monitoring. Volumetric capnography was recorded continuously using the NICO capnograph. In all animals both ventilatory modes (decelerating, PCV and square, VCV) were applied during 30 min in dif ferent order. Animals were ventilated with a tidal volume of 10 mL/kg, inspiratory/expiratory ratio (I/E) of 1/2, inspiratory time 0,5 seg, end-inspiratory pause 10 %, respiratory rate of 30 breaths/min, FiO2 of 50% and PEEP of 8 cmH2O af ter a RM of 40 cmH2O during 40 seconds. Data was collected at the beginning and at the end of each ventilatory mode. Statistical analysis: Wilcoxon and Friedman tests. Results and Discussion: Oxygenation was similar af ter both ventilatory modes (VCV: pO2 281,9 ± 19,9/ PCV: pO2 277,8 ± 23,1) and there were no dif ferences in the dead space ratio (VD/VT)(VCV: 0,72 ± 0,09/ PCV 0,71 ± 0,10). Mean airway pressure was analogous af ter PCV period (MAP 13,3 ± 0,5) and af ter VCV period (MAP 13,8 ± 1,0). All animals were hemodynamically stable with similar cardiac index af ter both ventilation modes (VCV 5,03 ± 1,08/ PCV 5,51 ± 1,01).

Concomitant assessment of depth of sedation with auditory evoked potentials monitor and Richmond Agitation-Sedation Scale in traumatic brain injury patients: A-789

depending on the use of exogenous catecholamines during the initial 24 hours. Six patients with superficial wounds without haemorrhage, served as controls. Results and Discussions: There was significant elevation of all cytokines studied, with group 1 showing the greatest values of IL-6 and IL-10, and the lowest values of TNF . No correlation was found with RTS and APACHE scores at admission, but this correlation was clear regarding IL-6 and IL-10, 2 hours later. IL-6 and IL-10 also correlated with the use of adrenergic drugs at 2 hours, while TNF at 4 hours after admission. ARDS development correlated only with IL-6 levels at 2 hours. There was no significant statistical difference regarding final outcome between the two groups. Conclusion(s): Catecholamine infusion during the early phase of haemorrhagic shock can influence TNF , IL-6 and IL-10 expression. IL-6 and IL-10 levels at 2 hours correlated with the severity of injury, but not with final outcome. References: 1 DeLong WG, Born CT. Clin Orthop 2004; 422: 57–65. 2 Rose S, Marzi I. Langenbecks Arch Surg 1998; 383: 199–208.